Switch



H.A A. THQRNBURG 2,086,752

SWITCH July 13, 1937.

Filed May 5, 1954 mvEN-roR l /ERBHL E Fiamma/P6 i n BY 4m" tion.

Patented July 1311937 f vUNITED*sfra'rlezs 'SWITCH i Herbal A. Thornburg, Anderson, Ind., assigner to General Motors CorporatiomfDetroit, Mich., i

a col'lwration of Delaware f Application May s, lsslifserial No. vagone 1oclaims (c1. zoo- 159) This invention relates to electric switches, and more particularly tofthelon'gitudinally reciprofeating type, 'and capableof handling `comparatively `heavy currents; suchlasis' employed in starting internal combustion engines.

An object of the present invention is to provide a full pressure contact, while the starting .motor circuit is` 'closed and which -is maintained at the terminals until the moment of release. f l l Another object of the present invention isto provide a switchhaving means yof effecting the release of the contacts without the possibility of ar'cng or burning of the contacts.

Further objects andadvantages of the present invention will beapparent from the following description, reference being had to the accompanyingdrawing wherein a preferred embodiment of the present invention is clearly shown.

yIn the drawing: 'Q'Fig.' 1 is a longitudinal sectionalview of the switch embodying the present inventionl and showing thefvarious parts in their normal posi-l Fig.` 2 is a View similar to Fig. 1, illustrating the switch in its operative and locked position.

Fig. 3 is a view similar to Fig. 2 illustrating the switch in its operative. andk locked position just prior to the switch beingunlocked andreturned to its normal position .indicated in dot-and-dash lines. *l Fig. 4 is a sectional view taken on the line 4-4 ofFig.1."`1

Referring to the drawing', the switch is shown comprising atubular housing or body I0 having `a shank 2|), a base 2| and a partition 22, vthe partition` dividing the housingfinto `anl upper vand a lower` chamber.y 'I'hepartition 22 is apertured i at'23 to form a bearing for a rodor shaft 24. A

coiled 'spring 25about the rod 24 is confined between thewpartition r22 and the under side of a washer 26 swaged intoan annular groove provided on the rod.` The' washer also operates to limit the movements of the rod in one direction.

Toward theV lowerV end' of the rod 24, which extends into the'base 2|' orlower rchamber of the housing, a contact memberor bar 2l is supported. This bar is insulated from the rod by washers 28. and bushings 29. The*` bar 21,v the washers 28 and bushings 29* are held togetherby'an eyelet 30 to form a movable contact assembly 3|. A

spring 32 is interposed betweentwo cup-shaped washers 33, the spring urging one of the washers 33 against a shoulder 34` provided by the rod andY the other .Washer against one side of the eyelet 3|). The spring 32 .constantly urges the contact assembly 3| toward a nut 35 screw threaded tothe rod `25` which holds the assembly 3|` uponthe rod. The spring 32 operates to prevent any injurious effects upony the contact Imember 21 when` same is vmoved toclose a circuit. 5`

The .base or lower chamber-2| is closed by. a plate 36 Vwhich insulatingly supports terminal bolts 3] and 38, the headsof which form stations ary vcontacts 39 and 40, respectively. The' bolts 3 7 andv 38 are connected to wires (notshown) of 10 an electric circuit which is tot be closed and openedby the operation of theswitch.- i

Theshankor upperchamber 2| is provided with internal threads to receive a nut 4|. This nut slidably supports an .actuating` member or 1.5 sleeve 42 having a stop 43, and an annular cam o r boss 44.` This sleeve also-has asliding iit on the upper end oi the. rod 24. The stop,4 3 limits the outward movement of the sleeve and is normally held against theabottom of the nut 4| by a coiled 20 spring 45 about the sleeve 42 and interposed between the top surface of the nut 4| and a cap 46 screw threaded to the sleeve.`

The shank 2| is provided with diametrically opposed slots 5llin which arms or latches 5| are 25 pivoted on pins 5 |a.A Each arm has a protrusion 52 adaptedto .cooperate with the cam 44 on the sleeve 42. The arms 5| areurged towardlj-:ach` other. byan extension spring 5 3` located within an external annular groove 54. provided by the 30 shank 2| and notches 55'formed in the arms 5|. The springis yieldingly held within theigroove by connecting its, hooked ends with each other. .f

A shell or sleeve 6 0 has a slidingr fit overthe shank 2| and encloses the arms and spring 5 3 ,to 35 protect same fromdirt and grease. This `sleeve also operates to keepthe spring 53 withinthe annular groove V54 and the notches 55 of thel arms 5|. The sleeve is held against a shoulder 6| providedby the shank 2| and maintained in position by a washerr 62. Tlfiiswasherextends overv the upper end of the sleeveand is clamped between the nut 4| and the top of the shank 2|.

The operation of the. switch will now be de-` scribed. Upon depression of the-cap 46 against thetension ofthe spring .45, the bottom ofV thesleeve 42 will bear againstv the washer 26 to force the rod 24 Vdownward as viewed in Figs. 1, 2 and 3, tor compress thespring 25. Upon continued downward movement of the rod the bar 2 1 will' engage 50 the stationary contacts 39 and 4 0 to close acirl cuit. On continued movement of the rod 24, the spring 32.will be compressed in order to protect themovablecontactfrom injurious. effects in case the operator exerts an exceedinglystrong force to 55 `surface `oi' the washer 26, thereby locking lthe switch in a closed position (see Fig. 2).

When the switch is closed, as illustrated in Fig.

2, the arms 5lkprevent the rod 24 from moving upward in case the operator should slightly release the pressure on the cap 46. When the operator does release the pressure on the cap 46, the

sleeve 42 will move immediately upward, as'

viewed in the drawing, due to the expansion of the spring 45, but the circuit will remain closed until the sleeve has moved a certain distance or until the cam is in the position shown in Fig. 3. On continued upward movement of the sleeve, due to the expansion of the spring 45, the cam 44 then cooperates with the protrusions 52 to force the arms outwardly therebyreleasing the arms 5I from engagement with the washer 26. When the arms 5| are free of the washer 26 the rod will move toward its normal position by the expansion of the spring 25. The force in which the spring 25 urges the rod 24 toward its normal position will cause the contact or bar 21 to move away from the stationary contacts quickly and clean to prevent arcing. The switch above described is especially -advantageous for heavy duty work, such as starting motor circuit for Diesel engines where al 32 volt f system is used. A'quick break must be made between the contacts in order to prevent arcing and burning of the contacts* While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow. f

What is claimed is as follows:

1. In an electric switch, the combination comprising; a housing, stationary contacts supported by the housing; aA rod slidably supported by the housing; a sleeve slidably supported by vthehousing and having a telescopic engagement with one end of the rod, said sleeve adapted to move in one direction actuating the rod in the same direction; a fiat movable contact insulatingly supported by the rod and adapted to gradually andwyieldingly bridge the stationary contacts; a spring for holding themovable contact away from the stationaryy contacts and adapted to be compressed on movement of vthe sleeve in one direction only; latching means carried by the housing for holding the rod against a slight axial movement when the movable contact is in engagement with the stationary contacts; and means carried by the sleeve for releasing the latching means when'the sleeve is moved in a reverse direction a certain distance allowing the spring to move the rod in the same direction and cause the contacts to separate.

2. -In an electric switch, the combination comprising; a tubular housing having a partition and dividing the housing into two chambers; a rod slidably supported by the dividing means; stationary contacts insulatingly supported within one of the chambers; a movable contact carried by the rod and adapted to gradually and yieldingly bridge the stationary contacts; a spring located in the other chamber and operating on the rod for holding the movable contact away from the stationary contacts; an actuating sleeve return movement when the contacts are in engagement; and means on the actuating sleeve for releasing the latching means when the sleeve has moved a predetermined distance in the'opposite direction to allow the compressed spring to move the rod in the same direction and separate the contacts. Q

3. In an electric switch; the combination comprising; a housing; a. pair of stationary contacts having dat surfaces; a rod slidably supported within the housing; a flat contact bar carried by the rod for bridging the contacts; a sleeve slidably supported by the housing and adapted to move therod against resilient means in one direction to compress a spring so as tov cause the bar to graduallyy bridge the stationary contacts; a latch for holding'the rod temporarily against movement while the bar is in contact position; cam means carried by the sleeve to engage and move the latch out of holding position when the sleeve has moved a predetermined distance toward its normal position to permit the spring to move the rod independently to separate the contacts.

4. In an electric switch of the class described, the combination comprising; stationary contacts; a movable contact; a shaft supporting the movable contact; locking means; aplunger having a cam; spring means resisting movement of the plunger; a second spring means; means to actuate the plunger, said plunger adapted to Vmove. the shaft in one direction to compress the A independently `and cause the movable contact to break quickly from the stationary contacts.

5. In a switch, the combination comprising; a casing; stationary contacts insulatingly supported by the casing; a rod slidably supported within the casing; a movable contact member insulatingly supported by the rod and adapted to bridge the stationary contacts; resilient means tending to resist movement of the rod; a plunger sleeve slidably supported Vby the casing and fitting over the rod, said sleeve having acam surface; resilient means outside of the casing tending to resist movement of the sleeve; a plurality of latches pivotally supported by the casing; an extension spring for moving the latches toward each other; and means for moving the plunger sleeve to actuate the rod to put the first mentioned resilient means under tension when the rod is moved in one direction to close a circuit and allowing the latches to engage means on the rod to prevent reverse movement' of the rod, and said plunger sleeve when moved in a reverse direction by the second mentioned resilient means a predetermined distance the cam will urge the latches away from each other to permit the rod to move in a reverse direction by the first mentioned kresilient means and cause .the movable `tionary contacts supported within one of the4 contact member to break quickly from the stationary contacts to open the circuit.

6. In an electric switch, the combination comprising; a tubular housing having a partition and dividing the housing into two compartments; a rod slidably supported by the partition; stacompartments; a movable contact carried by the rod to bridge the stationary contacts; a spring located in the other compartment and operating on the rod for holding the movable contact free of the stationary contacts; a sleeve slidably supported in the second mentioned compartment and adapted to move the rod in one direction to compress the spring and gradually urge the rod and movable contact in the same direction to bridge the stationary contacts; means for limiting the pressure applied to the contacts; arms pivotally supported by the housing; spring means for urging the arms toward each other, said arms cooperating with means carried by the rod to hold the rod against return movement and hold the first mentioned spring under a state of compression when the contactsare in engagement;

spring means for returning the sleeve; and means carried by the sleeve to urge the arms outwardly after the sleeve has moved in an opposite direction a certain distance to release the holding eiect of the Varms upon the rod'and allow the first mentioned spring to independently move the rod in a reverse direction to separate the contacts.

7. A switch comprising in combination; a housing; terminals supported bythe housing; a rod axially supported by the housing; a contact barslidably and yieldably supported on the rod; a spring within the housing for normally holding the contact bar out of engagement with the terminals, a plunger axially supported by the housing and having telescopic engagement with the rod; a second spring between the housing and one end of the plunger to hold the plunger at one limit of its movement; latching means supported by the housing; manual means for actuating theplunger in one direction for compressing both springs and gradually urge the rodand the contact barin the'same direction to bridge the terminals; and cam means carried by the plunger and so arranged as to cooperate with the `eviatching means and release the rod at a preder 'etermined point in the return movement of the fplunger and permit the rst mentioned spring expand and cause the rod and the contact bar to move independently of the plunger to quickly separate the contact bar from the vterminals.

8. In a switch of the class described the com- 4 lbination comprising; a tubular housing; a plunger longitudinally supported by the housing; arod longitudinally supported by the housing and having telescopic engagement with the plunger; a pair of sprint;.', each spring supported on the housing independent of each other to resist the movement of the plunger while only one spring resists the movement of the rod; manual means for actuating the plunger in one direction tomove the rod in the same direction for compressing both springs; a contact member carried by the rod; latching means adapted to engage a portion of the rod after the compression of the springs to lock the rod temporarily against return movement and hold the spring compressedthereby in a state of compression; means carried by the plunger for tripping the latching means when the plunger nears the end of its stroke in the return direction by one spring to allow the rod to' begin its return movement independent of the movement of the plunger by the other spring.

9. A switch comprising in combination; a tubular housing; terminals supported by the housing, an axially movable plunger; an axially movable bridging member adapted to make Contact with the terminals; a spring to yieldingly hold the plunger at one limit of its movement; a second spring to yieldingly hold the bridging member at one limit of its movement; latching means pivotally supported by the housing and adapted l member into engagement with the terminals; and

means projecting from the plunger for releasing the latching means when the plunger nears the end of its stroke in the return direction, the releasing of the latching means causes the second mentioned spring to move the bridging member independently of the plunger and the bridging member to break quickly from the terminals.

10. A switch comprising in combination; an actuator; ar movable contact; terminals for the contact; a springfor resisting movement of the actuator in one direction; a second spring for resisting movement of the contact in the same direction; a latch mechanism supported with respect to the contact, said latch mechanism adapted to temporarily hold the contact in engagement with the terminals and to hold the second mentioned spring in a state of compression when HERBAL A. THORNBURG. 

